The importance of development and improvement of cells has been increasing in various industries such as the mobile device industry and the automobile industry in recent years. This trend has brought various newly developed or improved cell systems that are excellent, in particular, in cell performance and secondary cell design.
As cells have become widespread, zinc anodes containing a zinc species as an anode active material have been one of the subjects of studies. Examples of cells including a zinc anode include primary cells, secondary cells (storage cells), and air cells. Specifically, cells such as zinc-air cells that use atmospheric oxygen as a cathode active material, nickel-zinc cells containing a nickel-containing compound as a cathode active material, manganese-zinc cells and zinc ion cells which contain a manganese-containing compound as a cathode active material, and silver-zinc cells containing silver oxide as a cathode active material have been developed and studied. In particular, zinc-air primary cells, manganese-zinc primary cells, and silver-zinc primary cells are in practical use in a wide area of the world. Additionally, the recent increasing importance of development and improvement of cells in various industries, such as the mobile device industry and the automobile industry, has brought various newly developed or improved cell systems that are excellent, in particular, in cell performance and secondary cell design.
Nickel-zinc cells, which contain a nickel-containing compound as a cathode active material, and zinc-air cells, which use air (oxygen) as a cathode active material, are advantageous among others in terms of the following points: safety is ensured by the use of an alkaline aqueous solution; and no rare metal is used in the electrode material as an elemental strategy. A disadvantage thereof is that zinc dendrites grow in the zinc anode to cause a short circuit.
Various technical developments have been made to solve the problem (for example, Patent Literatures 1 to 13 and Non Patent Literature 1). Besides, various studies and developments in members of the electrodes, such as active material layers, have been made (for example, Patent Literatures 14 to 18).